David,
You can buy the trap mirrors brand new available for the passenger side. As far as the dimensions, here is the diagram I obtained from CD here on the FAQ.

The mirror will have the mounting bracket and gasket short of the cage nuts that mount the bracket to the door so you need to get them separately.
If you do a search on this forum you can find more pointers. It needs to be done properly so the mirror doesn't shake or fall off.

I had mine done at the body shop as I was afraid to crack the paint while drilling holes.

Good luck
Hamada
_________________
E36M3 535im 70Bristol02